Dolly the sheep was undoubtedly the world's most famous sheep – but how did she come to be, and what did she mean to her creator, Professor Sir Ian Wilmut?

Twenty years on from Dolly's birth, Professor Jim Al-Khalili gets to know the 'father of the sheep that had no father' in front of an audience at Edinburgh Festival.

While studying for a general agricultural degree at Nottingham University, Professor Wilmut realised that he wasn't suited for business and much preferred the scientific side of agriculture to farming. His PhD project involved finding ways of freezing pig semen to ensure that the sperm retained their motility after thawing. This led to work on freezing embryos and the birth of a calf, fittingly named Frosty. Professor Wilmut points out that this sort of freezing technique – although refined slightly – is still used to freeze surplus human embryos after IVF.

In 1982, a new director took over the Roslin Institute, Scotland, where Professor Wilmut was working. The director insisted that Professor Wilmut stop his freezing research and instead join the 'molecular genetics boom'. He says that this made him very unhappy at the time, but obviously 'things have worked out really well!'

Interestingly, Dolly was not actually the first cloned sheep. Professor Wilmut explains that, over a decade before Dolly, Dr Steen Willadsen at the Institute of Animal Physiology in Cambridge used cells from early embryos to clone sheep by nuclear transfer. However, Dolly was the first clone to be produced using a nucleus from an adult sheep cell, which completely overturned the assumption that cell differentiation was irreversible. Her creation also showed that there are factors in the egg that can change the function of the differentiated nucleus. Professor Wilmut explains that this knowledge has helped lead to the creation of induced pluripotent stem (iPS) cells, which are becoming increasingly important for studying inherited diseases.

Although most of the audience probably know the answer, Professor Jim Al-Khalili asks about Dolly's namesake. 'The cell that was used to provide the genetic information came from mammary tissue, and she was named Dolly in view of the spectacular mammary tissue that Dolly Parton had,' explains Professor Wilmut. 'Dolly Parton's manager is reputed to have said, "There's not such thing as baaad publicity!"'

I was surprised to hear that Professor Wilmut was not present at Dolly's birth, but instead was digging in his vegetable patch! He explains that this was because the hill sheep his team kept weren't very used to humans, so they limited the number of people that could be present with the sheep at any one time.

The cloning procedure often resulted in miscarriages and post-natal problems; Professor Wilmut describes the case of a ram lamb that wouldn't stop panting, even when resting. He admits that this did not personally distress him, but he felt disappointed that the cloning technique was not more successful.

Although Dolly was created as a means to an end, Professor Wilmut says that he was saddened when she had to be put down at six years old. Sheep normally live for about 12 years but Dolly had contracted a viral cancer that was known to be present within Scotland at the time. He explains that this was 'no reason whatsoever to do with cloning'.

I was amazed to hear that Professor Wilmut thinks that it is currently possible to clone humans. 'But I would question the reasons someone would want to do it, because of the effect on the cloned child, but also because there is probably another way of achieving same objective,' he said.

Overall, I found the show light-hearted and easy to listen to. It was interesting to hear Professor Wilmut talk about the impact that Dolly has had on the stem cell field; I personally had not given this much thought before. Professor Jim Al-Khalili was also a good host, asking a range of questions. I am not usually a radio listener but I'm now tempted to try some of his other shows.

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